src/lib/guid.c

	guid.c revision efaa1272c1b682bc2e105b2f374152a6a1f45825
/* Copyright (c) 2011-2014 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "buffer.h"
#include "sha1.h"
#include "hash.h"
#include "hex-binary.h"
#include "hostpid.h"
#include "guid.h"

#include <unistd.h>
#include <time.h>

const char *guid_generate(void)
{
    static struct timespec ts = { 0, 0 };
    static unsigned int pid = 0;

    /* we'll use the current time in nanoseconds as the initial 64bit
       counter. */
    if (ts.tv_sec == 0) {
        if (clock_gettime(CLOCK_REALTIME, &ts) < 0)
            i_fatal("clock_gettime() failed: %m");
        pid = getpid();
    } else if ((uint32_t)ts.tv_nsec < (uint32_t)-1) {
        ts.tv_nsec++;
    } else {
        ts.tv_sec++;
        ts.tv_nsec = 0;
    }
    return t_strdup_printf("%04x%04lx%04x%s",
                   (unsigned int)ts.tv_nsec,
                   (unsigned long)ts.tv_sec,
                   pid, my_hostname);
}

void guid_128_host_hash_get(const char *host,
                unsigned char hash_r[GUID_128_HOST_HASH_SIZE])
{
    unsigned char full_hash[SHA1_RESULTLEN];

    sha1_get_digest(host, strlen(host), full_hash);
    memcpy(hash_r, full_hash + sizeof(full_hash)-GUID_128_HOST_HASH_SIZE,
           GUID_128_HOST_HASH_SIZE);
}

void guid_128_generate(guid_128_t guid_r)
{
#if GUID_128_HOST_HASH_SIZE != 4
#  error GUID_128_HOST_HASH_SIZE must be 4
#endif
    static struct timespec ts = { 0, 0 };
    static uint8_t guid_static[8];
    uint32_t pid;

    /* we'll use the current time in nanoseconds as the initial 64bit
       counter. */
    if (ts.tv_sec == 0) {
        if (clock_gettime(CLOCK_REALTIME, &ts) < 0)
            i_fatal("clock_gettime() failed: %m");
        pid = getpid();

        guid_static[0] = (pid & 0x000000ff);
        guid_static[1] = (pid & 0x0000ff00) >> 8;
        guid_static[2] = (pid & 0x00ff0000) >> 16;
        guid_static[3] = (pid & 0xff000000) >> 24;
        guid_128_host_hash_get(my_hostdomain(), guid_static+4);
    } else if ((uint32_t)ts.tv_nsec < (uint32_t)-1) {
        ts.tv_nsec++;
    } else {
        ts.tv_sec++;
        ts.tv_nsec = 0;
    }

    guid_r[0] = (ts.tv_nsec & 0x000000ff);
    guid_r[1] = (ts.tv_nsec & 0x0000ff00) >> 8;
    guid_r[2] = (ts.tv_nsec & 0x00ff0000) >> 16;
    guid_r[3] = (ts.tv_nsec & 0xff000000) >> 24;
    guid_r[4] = (ts.tv_sec & 0x000000ff);
    guid_r[5] = (ts.tv_sec & 0x0000ff00) >> 8;
    guid_r[6] = (ts.tv_sec & 0x00ff0000) >> 16;
    guid_r[7] = (ts.tv_sec & 0xff000000) >> 24;
    memcpy(guid_r + 8, guid_static, 8);
}

bool guid_128_is_empty(const guid_128_t guid)
{
    unsigned int i;

    for (i = 0; i < GUID_128_SIZE; i++) {
        if (guid[i] != 0)
            return FALSE;
    }
    return TRUE;
}

bool guid_128_equals(const guid_128_t guid1, const guid_128_t guid2)
{
    return memcmp(guid1, guid2, GUID_128_SIZE) == 0;
}

int guid_128_from_string(const char *str, guid_128_t guid_r)
{
    buffer_t buf;

    buffer_create_from_data(&buf, guid_r, GUID_128_SIZE);
    return strlen(str) == GUID_128_SIZE*2 &&
        hex_to_binary(str, &buf) == 0 &&
        buf.used == GUID_128_SIZE ? 0 : -1;
}

const char *guid_128_to_string(const guid_128_t guid)
{
    return binary_to_hex(guid, GUID_128_SIZE);
}

unsigned int guid_128_hash(const guid_128_t guid)
{
    return mem_hash(guid, GUID_128_SIZE);
}

int guid_128_cmp(const guid_128_t guid1, const guid_128_t guid2)
{
    return memcmp(guid1, guid2, GUID_128_SIZE);
}